With development of computing technology, it is more and more dependent on computer aided methods in dental area. For instance, in orthodontic area, three dimensional (3D) digital models of teeth are used in many cases. One example is that dental appliances, such as shell shaped retainers and teeth repositioners, can be manufactured basis 3D digital models of jaws.
Most often used methods for obtaining a 3D digital model of a patient's jaw include: scanning a plaster cast fabricated basis a dental impression; scanning a dental impression directly; and scanning the patient's jaw directly. However, due to limited precision of scanning and residual material etc., in a 3D digital model of a jaw obtained by the above methods, surfaces of adjacent teeth may be joined. To utilize a 3D digital model of a jaw, in many cases, it requires to separate teeth from each other. For adjacent teeth that are joined, their joined part surfaces need to be reconstructed after separation, such that shape of a tooth with a reconstructed joined part surface is more similar to the real tooth. Unfortunately, currently effective method for reconstructing joined part surfaces of two adjacent teeth is not available.